Pouch

Any links below to external sites are offered for your convenience but the Musical Museum neither endorses the sites nor vouches for the accuracy of their content.

The soft leather membrane about 20mm diameter glued across a hole in the valve chest or stack of a player piano. It is drawn in when a hole in the piano roll coincides with a hole in the tracker bar, and lifts the valve opposite it to allow the suction inside the valve chest to be applied to the pneumatic which collapses to operate the piano action for the relevant note.